The present invention relates to a powdered composition for food and drink which comprises powdered soy protein isolate, an anthocyanin-containing powder, and an organic acid. More particularly, it relates to a powdered composition for food and drink which is dissolved or suspended in water, milk, etc. to stably provide a drink with a bright color developed by an anthocyanin pigment present in the anthocyanin-containing powder.
Although powdered soy protein isolate is widely used for food and drink for health maintenance, it is hard to take as such because of its peculiar beany flavor. Therefore, compositions containing soy protein isolate together with fruit components such as fruit juice or comminuted fruit for making the composition easy to take have been manufactured and commercially sold. Fruits used in combination with soy protein isolate are usually selected from those are rich in nutriment, such as vitamins, and contain a relatively vivid color juice.
Such fruits include blueberries and cranberries. They not only contain nutriment such as various vitamins but assume an appetizing bright reddish purple color. Of the pigments contained in these fruits, anthocyanins, which are glycosides of anthocyanidins, have now been turned out to possess various physiological functions, such as a rhodopsin (visual purple) resynthesizing function, a capillary protecting function, an anti-ulcer function, a circulatory organ improving function, an anti-inflammatory function, and a vitamin P-like function as reported, e.g., in 2nd Blueberry Function Symposium, held by Japan Blueberry Association at Minami Aoyama Kaikan in Minato-ku, Tokyo on Apr. 24, 1998. Addition of powder of such fruit containing an anthocyanin to soy protein isolate provides a powdered composition for food and drink which has the functions of soy protein isolate supplemented by the above-mentioned various functions and is easy to take.
However, when a powdered composition containing soy protein isolate and an anthocyanin-containing powder (e.g., an anthocyanin-containing fruit powder) is dissolved or suspended in water, milk, a sports drink, etc., the bright reddish purple color characteristic of anthocyanin pigments hardly develops but results in pale gray. Where the powdered composition is supplemented with minerals such as calcium and magnesium by addition of dolomite, calcium carbonate, magnesium carbonate or coral minerals, on dissolving or suspending the powdered composition in a liquid, such as water, milk, or sports drink, the mineral components will dissolve in the liquid to show a strong alkaline property, which makes the color unpleasantly grayer.
Equal in nutrition, nevertheless, such poorly colored drinks cannot be seen as appetizing and are likely to look like deteriorated in quality, which reduces consumers"" willingness to buy. As for an anthocyanin itself, which is a reddish purple pigment of the anthocyanin-containing powder, it sometimes decomposes with time to reduce the above-described various physiological functions. From this viewpoint, it has been desired to stabilize anthocyanins.
An object of the present invention is to provide a powdered composition for food and drink containing powdered soy protein isolate and an anthocyanin which develops a bright reddish purple color characteristic of an anthocyanin pigment when dissolved or suspended in water, milk, a sports drink, etc. for drinking, and in which the anthocyanin is stable with time to retain its various physiological functions.
The present inventors have conducted extensive studies to accomplish the object and found as a result that the above-described problems are settled by incorporating an organic acid, such as citric acid, into the composition of powdered soy protein isolate and an anthocyanin-containing powder. The present invention has been completed based on this finding.
The present invention provides a powdered composition for food and drink which comprises powdered soy protein isolate, an anthocyanin-containing powder, and an organic acid. While it is known that an anthocyanin itself satisfactorily develops a reddish purple color in an acidic condition, improvement on color development of an anthocyanin in the presence of powdered soy protein isolate is utterly unknown.
The powdered soy protein isolate which can be used in the present invention is not particularly limited in process of preparation. Any product containing powdered protein isolated from soybeans in a conventional manner can be used. Useful powdered soy protein isolates include a product prepared by extracting defatted soybeans (residue after removing soybean oil from whole soybeans) with water to remove saccharides, etc., separating protein with an acid, neutralizing the isolated protein, followed by sterilization and drying; a textured soy protein product prepared by extruding soy protein isolate followed by drying and granulating; and a soy peptide product prepared by enzymatically or chemically degrading a part or the whole of soy protein isolate followed by sterilizing and drying. Commercially available powdered soy protein isolates which can be used in the present invention include SUPRO 710, Fujipro, Proleena, Fujinix, Apex, and Hinute (all available from Fuji Protein Technologies Inc.).
The anthocyanin-containing powder which can be used in the present invention is not particularly limited as long as it contains an anthocyanin, including powdered products obtained from plant parts containing an anthocyanin, such as fruit, fruit juice, petals and leaves, by usual means such as lyophilization or hot air drying, and purified products obtained by extracting these plant parts. Preferred examples of anthocyanin-containing powders are powder prepared by drying juice or extract of cranberries having a urinary infection prophylactic function and powdered blueberry juice. Such anthocyanin-containing powder products are commercially available under trade names of Cranberry Powder (available from Kikkoman Corp.) and Blueberry Powder (available from Nihon SiberHegner K. K.). In addition, Hibiscus Funmatsu (powdered hibiscus petals, available from Biocon (Japan) Ltd.), Shiso-no-ha Funmatsu (powdered perilla leaves, available from Amino Up Chemical Co., Ltd.) and Murasaki-imo Powder (powdered purple sweet potato (Ipomoea batatas Poir), available from Senba Foods Co., Ltd.) are also useful.
The organic acid which can be used in the present invention preferably includes those which are usually crystalline or powdery, such as citric acid, tartaric acid, and malic acid, seeing that the composition of the invention has a powder form. Organic acids which are usually liquid may be made usable by, for example, granulating as a cyclodextrin inclusion compound. Of the useful organic acids citric acid, tartaric acid and malic acid are particularly preferred for their flavor when incorporated into the powdered composition as demonstrated later. Mineral acids, such as hydrochloric acid and sulfuric acid are also capable of letting anthocyanin pigments develop their bright reddish purple colors when the powdered composition is dissolved or suspended. However, they give an unacceptably irritating taste and is unfit for application to the powdered composition for food and drink.
The mixing ratio of the powdered soy protein isolate, the anthocyanin-containing powder, and the organic acid is not particularly limited. It is arbitrarily selected according to the intended use of the powdered composition and the desired degree of color development by the anthocyanin on dissolving or suspending. Seeing that, in general, compositions of this type comprise powdered soy protein isolate as a main component and anthocyanin-containing powder as a supplementary component for making the composition easy to take, the formulation of the powdered composition of the present invention usually comprises about 50 to 95% by weight of powdered soy protein isolate, about 4 to 49% by weight of an anthocyanin-containing powder, and about 2 to 20% by weight of an organic acid each based on the total powdered composition. Higher contents of the anthocyanin-containing powder and the organic acid generally result in development of a denser color on dissolving or suspending the powdered composition in water and the like.
In order for the powdered composition to provide a palatable liquid with an appropriate color tone, the organic acid content in the powdered composition preferably ranges from 2.0 to 20.0% by weight. For example, where 10 g of powdered soy protein isolate and 2 g of an anthocyanin-containing powder are mixed, a preferred amount of an organic acid added is about 0.25 to 3.0 g. In this case, the resulting powdered composition consists of 66.7 to 81.6% by weight of soy protein isolate, 13.3 to 16.3% by weight of the anthocyanin-containing powder, and 2.0 to 20.0% by weight of the organic acid.
The powdered composition of the present invention is dissolved or suspended in a liquid, such as water, milk, and a sports drink containing phosphates, minerals, vitamins, etc., to provide a palatable drink with a pleasant color. In particular, incorporation of the organic acid is extremely effective on color development where the powdered composition further comprises mineral components showing strong alkalinity, such as dolomite, calcium carbonate, magnesium carbonate and coral minerals for mineral supplement, because anthocyanin pigments hardly develop their characteristic colors when dissolved or suspended in the presence of such an alkaline substance. An adequate intake of the powdered composition for food and drink according to the present invention as a health maintenance food is generally about 10 to 50 g in terms of soy protein isolate per day for an adult, while somewhat varying depending on the formulation.
Since the color development of the powdered composition of the invention is attributed to organic acid-aided development of a color of a naturally-occurring pigment but not to artificial colorants as has been usual with this type of food and beverages, the powdered composition is highly safe. Further, the anthocyanin glycoside itself can be stabilized by rendering the powdered composition acidic, thereby keeping the above-described physiological activities during storage. Therefore, the powdered composition of the present invention is extremely beneficial as a health maintenance food.